Microprocessor-based controls are used with automotive vehicle engines to perform various functions. One of the functions that has heretofore been proposed for such controls is programmed starting. Programmed starting comprises an algorithm that is executed by the microprocessor when the driver starts the engine, principally to prevent the driver from operating the engine throttle in a way that might adversely affect the starting process. The control is configured to conduct the engine starting procedure in a predetermined manner defined by the algorithm so that the starting procedure is unaffected by the driver's actions during that time. Basically, the control preempts the driver's actions. Once the starting procedure has been successfully completed, full control of the throttle reverts to the driver.
Another function that has heretofore been proposed for microprocessor-based engine controls is programmed vehicle launching. As applied to an automotive vehicle which has a manual transmission, programmed vehicle launching comprises placing both the clutch function and the throttle function under the control of the microprocessor during launch. The microprocessor executes an algorithm that has been predetermined to produce a satisfactory launch.
The incorporation of a programmed launch function in a vehicle comprises not only the development of an algorithm for automating both throttle operation and clutch operation, but also suitable clutch and throttle actuators for performing respective clutch and throttle operations to the exclusion of the clutch and accelerator pedals that are used by the driver. For this reason, the system must of necessity be somewhat complex, and complexity invariably adds to the cost. Moreover, it is a difficult task to write an algorithm that will operate a clutch and throttle satisfactorily for the many different types of launch situations that a driver may encounter. Yet the manner in which a clutch and throttle are operated during launch has a very significant influence on clutch life and performance.
The problem of accelerated clutch wear and tear is typified by the experiences of fleet operators. Different drivers may launch a truck in different ways. Some may be especially careful in conducting a launch; others, less so. One significant cause of accelerated clutch wear and tear is repeated clutch engagements at too high an engine speed. The particular type of clutch may also be a factor in determining the best engine speed for launch.
Because improper clutching can accelerate wear and tear on the clutch, and other powertrain components too, it continues to be a desirable objective to have some sort of algorithm-controlled launch.